Creating WebService for a EJB???----URGENT plz

hellow....

i'm a begginer in EJBs and also web-services......

i know how to program an EJB but donno abt how to test it in NWDS....

i wrote some business logic methods.....but i donno how to create web-services for

the created EJB and test the functionality.....

thers only one business method returning a string..in my Stateless session bean.

but i cudnt create a webservice for this...and the use of it.....

can some one present me the CONCEPT oriented explanation of web-service...

how to create it....

what is Vertual interface...??

what is Web-service definition??

what is web-service configuration??

why shud we create them??

and finally how to call my business method... after deploying the EJB??

some useful links may also help.....

i'll highly appreciate if explained clearly in the forum itself........

thanx in advance.....

regards,

Sudheer